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New pool owner, weird readings?

As you can see in my post, my pool was filled 2 days ago. My teenager girls were swimming in it as it filled. I do not have leaves anywhere near my pool, and it is in full sun a lot of the day. I will be ordering a better test kit asap, but in the meanwhile all the local stores had at this time of the season is the htp test strips. I also have an old KH test from my fish tanks from a few years ago, but not sure that would still be valid results. Put 2 gallons of walmart 8.25% bleach in this morning. Came home this afternoon, FC still read 0. Added 1 more gallon, as per pool math site. Waited 30 min. At this point test strips are reading: FC 5 PH 7.5 TH 100 TA somewhere between 120 and 180. CYA 30 - 50. Waited another 30 min to 1 hour. Results were totally different. FC was down to 1. PH up to 8.4, and CYA 0. Added 2 more gallons of bleach. After another 30 min + FC 10+ PH 8.4, TA 180 TH100 CYA somewhere between the 30- 50 reading and the 100 reading. I know bleach is not supposed to raise CYA, but it is the only thing I have added to the pool? Also color went from completely clear before bleach added to a slightly yellow color, I assume because of the bleach color? So do I still need to get CYA? and is there another form of acid that would be readily available at this time of year in a small town?

Re: New pool owner, weird readings?

I have about the same size pool as yours. for every 8 oz cup of 8.25% Bleach you add you are adding 0.7ppm of FC. If you dumped 3 121oz jugs in 2 days your FC is out of sight. (that is 254ppm). I would not trust those test strips.
I would definitely be getting a Good test kit. I use the TF100 with a speedstir. You can get one at TFTestkits.com
If you added three jugs of chlorine Do not let anyone swim in that pool until you can get it confidently tested. Most of the Yellow drop chlorine testers are not accurate beyond 5ppm and you have exponentially way more than that.

Re: New pool owner, weird readings?

Based on your posting, you did not add any CYA, so yes, you must add some. 2 lbs granular or 3 qts liquid will get you to near 40ppm CYA according to the PoolMath calculator (link at the top of the page). If you use granular, place it in sock(s) and suspend them in the flow path of a return or your skimmer. I seem to recall the half life of FC without CYA in sunlight is 30 minutes. So your massive overdose of CL may be gone at this point, or will be soon.

Re: New pool owner, weird readings?

After the 5th gallon last night, at sundown FC read 10+ and CYA between 50 and 100. Same results this morning. When I got back at 4 both were back to 0. Re-added a bottle of 3%, that is all I have left until I can get to Walmart (45 min. away) as no cyA available closer than that. Walmart will not have CYA this time of year either, I suspect. I will be there tomorrow, hopefully it can wait until then. I will see if there are any better test kits in Owasso or Skiatook too. Otherwise if I order online today, it will be a week without test results to go on until the new kit comes in the mail.

Re: New pool owner, weird readings?

I hope you ordered that test kit. CYA 50-100 isnt going to help us to guide you through this. You also need to manage FC levels in the double digits to fix this, and no strip or pool store is going to help with that.

Re: New pool owner, weird readings?

Test kit ordered. Meanwhile, today purchased cya and dry acid (Ph down - sodium sulfamide). Put some CYA in sock and tied to pool. After an hour or so, added 2 gal. bleach. On test strip, FC now 10+ again. Assuming I should wait on adding the PH down until the chlorine/CYA acid issue is fixed? Will CYA also lower PH?

Re: New pool owner, weird readings?

Ok, let's start with this... Welcome to the forum

I think you've now become an example of why no one here has any confidence in test strips. Even with the strips you are functionally flying blind until you can get better test tool. Don't panic, I've recently done the very same. In the short term - STOP ADDING CHEMICALS. You don't know your current chemistry so you can't predict how the additions will change it.

You filled it very recently, that means we can make a pretty good guess of your current chemistry (better than the test strips you're using, anyway ) just by adding up everything you've added, can you give us a complete list?

When it comes down to it, the first priority in pool water chemistry is sanitation. You've definitely added enough chlorine to assure that for the moment. Second is probably pH and somewhere lower on the priority ladder is things like water quality, calcium hardness/scaling, corrosion, and maintenance costs. (anyone should feel free to start a new thread to argue those relative priorities )

Chlorine gets used up mostly through sunlight and doing it's job. You will have to add more pretty much daily. Your target levels and how much get consumed by sunlight exposure depends mainly on your levels of CYA (which we really don't know right now) Assuming that your water is reasonably clear at the moment, not a green monster, a fair guess is going to be about 1/2 a gallon of 8.25% bleach per day. And I'd suggest adding in the evening so it can work all night before fighting the sun. That should add about 6ppm of free chlorine. That should be enough to hold things steady for a few days till you can get a decent test kit.

If you see anything nasty in the water - algae, lots of leaves, dead animals, whatever, go ahead and increase your bleach to a whole gallon a day.

I think ranger_ric dropped a decimal point somewhere. Poolmath says three gallons of 8.25% bleach in a 6500 gallon pool is about 40ppm. This is still high, but not quite OMG scary high. But not knowing how much CYA you have or how much sunlight your pool gets... it's all guesswork until you get a trustworthy test result.

Re: New pool owner, weird readings?

Thank you for all the help! Chemicals added to date: 8.25% bleach ( a lot). Thanks for the recommendation of 1/2 gal. per day. Lately I have been adding in the evening, or 30 min. or so before swimming. Thankfully, with school starting, my teenagers now have a lot less time to swim.
Only other thing I have added is a sock about 2/3 full of CYA 100% Test kit has been shipped, so hopefully will have better results soon. Will wait on adding PH down until test kits here and chlorine/cya stabilized. Thanks again!

Re: New pool owner, weird readings?

Uhmm... ok. "a lot" and "sock about 2/3 full" aren't really numbers I can use to estimate your current water chemistry. Well, I could, but the accuracy is going to be about as good as the test strips you've been using

Clearly you have _some_ CYA. That gives me a bit more confidence in the flying blind -1/2 gallon a day suggestion. When you get your test kit in a few days, post the results and you'll get a lot better advice.

Re: New pool owner, weird readings?

Well, new test kit is here. TF-50. Did CYA test first, filled to bottom of mixing bottle label with pool water, to top with reagent. Mixed, waited well over 30 sec, mixed again. Filled view tube all the way and still could see dot, so assuming 0 cya still. Sock full of CYA is almost gone though, and has been in pool since Tuesday night, so where is it going? Pump running 24x7 until everything stabilized, and my daugter and I got in last night to make sure everything was well circulated. Other test results:
FC 3 after 24 hours of 0 cya and only 1/2 gal. added last night? CC - 0.5 CH 125 TA 14 drops turned solution slightly pink, 15 drops turned it red, so 140 - 150 depending on if it has to be a full red or not.
To compare, test strips show Total hardness 100, consistently. FC 1 PH 7.5. TA 180 consistently. CYA 0. So do I add more CYA today or wait a few more days?

Re: New pool owner, weird readings?

CYA can take several days to show up properly on a test. Assume it's at the level you targeted, using PoolMath I hope. Keep the FC up at the proper level for your now assumed CYA until you can get a good test. Probably have to order more reagent soon as the TF-50 doesn't come with much IIRC.

Re: New pool owner, weird readings?

Thanks. I do remember seeing somewhere on the site that cya can take like a week to register? So I can wait a few days and retest, right? Hopefully it will get up sooner rather than later so it stops eating chlorine. This is the first day I haven't had it back to 0 by the end of the day.

Re: New pool owner, weird readings?

Re: New pool owner, weird readings?

Cut and paste from pool school: CYA - Cyanuric Acid

Cyanuric acid, often called stabilizer or conditioner, both protects FC from sunlight and lowers the effective strength of the FC (by holding some of the FC in reserve). The higher your CYA level, the more FC you need to use to get the same effect. It is important to know your CYA level so you can figure out what FC level to aim for. If you don't have a SWG or problems from extremely high amounts of sunlight, CYA is typically kept between 30 and 50. If you have a SWG or very high levels of direct sunlight, CYA is typically kept between 70 and 80.

You increase CYA by adding cyanuric acid, often sold as stabilizer or conditioner. CYA is available as a solid and as a liquid. The liquid costs a lot more, and generally isn't worth the extra expense. Solid stabilizer can take up to a week to fully register on the test, so don't retest your CYA level for a week after adding some. Solid stabilizer is best added by placing it in a sock in the skimmer basket. The pump should be run for 24 hours after adding solid stabilizer and you should avoid backwashing/cleaning the filter for a week.